Transflective liquid crystal display device and method of fabricating the same

ABSTRACT

An array substrate for a transflective liquid crystal display device includes: a substrate; a gate line and a data line on the substrate, the gate line and the data line crossing each other to define a pixel region including a transmissive area and a reflective area surrounding the transmissive area; a thin film transistor having a gate insulating layer, the thin film transistor electrically connected to the gate line and the data line; a first passivation layer having a drain contact hole exposing a drain electrode of the thin film transistor and a through hole exposing the substrate in the transmissive area; a pixel electrode on the first passivation layer, the pixel electrode contacting the substrate in the transmissive area through the through hole; and a reflective plate on the pixel electrode, the reflective plate being electrically connected to the drain electrode through the drain contact hole and to the pixel electrode.

This application claims the benefit of Korean Patent Application No.2005-0084196, filed on Sep. 9, 2005, which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) deviceand a method of fabricating a liquid crystal display device, and moreparticularly, to an array substrate for a transflective liquid crystaldisplay device and a method of fabricating the same.

2. Discussion of the Related Art

As the information age advances, display devices for displayinginformation are actively being developed. More particularly, flat paneldisplay (FPD) devices having a thin profile, light weight and low powerconsumption are actively being pursued. FPD devices can be classified aseither an emissive type or a non-emissive type depending on their lightemission capability. In an emissive type FPD device, an image isdisplayed using light that emanates from the FPD device. In anon-emissive type FPD device, an image is displayed using light from anexternal source that reflects and/or transmits through the FPD. Forexample, a plasma display panel (PDP) device is a field emission display(FED) device. In another example, an electroluminescent display (ELD)device is an emissive type FPD device. Unlike a PDP and an ELD, a liquidcrystal display (LCD) device is a non-emissive type FPD device that usesa backlight as a light source.

Among the various types of FPD devices, liquid crystal display (LCD)devices are widely used as monitors for notebook computers and desktopcomputers because of their high resolution, color rendering capabilityand superiority in displaying moving images. The LCD device displaysimages by controlling a transmittance of light through the device. Moreparticularly, liquid crystal molecules of a liquid crystal interposedbetween two substrates facing each other control light transmission inresponse to an electric field generated between electrodes on one of thesubstrates.

Because the LCD device does not emit light, the LCD device needs to beused with a separate light source. Thus, a backlight is disposed on therear surface on a liquid crystal panel of the LCD device, and images aredisplayed with the light emitted from the backlight and transmittedthrough the liquid crystal panel. Accordingly, the above-mentioned LCDdevice is referred to as a transmission type LCD device. Thetransmission type LCD device can display bright images in a darkenvironment due to the use of a separate light source, such as abacklight, but may cause a large power consumption because of the use ofthe backlight.

To solve the problem of large power consumption, a reflection type LCDdevice has been developed. The reflection type LCD device controls atransmittance of light by reflecting the outside natural light orartificial light through a liquid crystal layer. In a reflection typeLCD device, a pixel electrode on a lower substrate is formed of aconductive material having a relatively high reflectance and a commonelectrode on an upper substrate is formed of a transparent conductivematerial. Although the reflection type LCD device may have lower powerconsumption than the transmission type LCD device, it may have lowbrightness when the outside light is insufficient or weak.

To solve both the problems of large power consumption and lowbrightness, a transflective LCD device combining the capabilities of atransmission type LCD device and reflection type LCD device has beensuggested. The transflective LCD device can select a transmission modeusing a backlight while in an indoor environment or a circumstancehaving no external light source, and a reflection mode using an externallight source in an environment where the external light source exists.

FIG. 1 is a cross-sectional view of an array substrate for atransflective LCD device according to the related art. In FIG. 1, asubstrate 10 includes a pixel region “P” defined by a crossing of a gateline (not shown) and a data line 30. The pixel region “P” includes areflective area “RA” and a transmissive area “TA.” The reflective area“RA” includes a transistor area “TrA.”

A thin film transistor (TFT) “Tr,” including a gate electrode 15, a gateinsulating layer 20, a semiconductor layer 25, a source electrode 33 anda drain electrode 36, is formed on the substrate 10 in the transistorarea “TrA.” The semiconductor layer 25 includes an active layer 25 a andan ohmic contact layer 25 b. A first passivation layer 39 of aninorganic insulating material is formed on the TFT “Tr” and a secondpassivation layer 45 of an organic insulating material is formed on thefirst passivation layer 39. Subsequently, a through hole “TH” is formedin the second passivation layer 45 within the transmissive area “TA.”Further, the second passivation layer 45 includes a drain contact hole47 exposing the drain electrode 36 and an uneven top surface. A thirdpassivation layer 49 of an inorganic insulating material is formed onthe second passivation layer 45 and has the drain contact hole 47exposing the drain electrode 36. A reflective plate 52 of a reflectivemetallic material layer is formed on the third passivation layer 49. Thereflective plates 52 in the adjacent pixel region “P” are separated fromeach other. A fourth passivation layer 55 of an inorganic insulatingmaterial is formed on the reflective plate 52, and a pixel electrode 60is formed on the fourth passivation layer 55. The pixel electrode 60 isconnected to the drain electrode 36 through the drain contact hole 47.As a result, a gate insulating layer 20 of the thin film transistor(TFT) “Tr,” the first passivation layer 39, the third passivation layer49, the fourth passivation layer 55 and the pixel electrode 60 aresequentially formed on the substrate 10 in the transmissive area “TA.”

FIGS. 2A to 2F are cross-sectional views showing a fabrication processof an array substrate for a transflective LCD device according to therelated art. As shown in FIG. 2A, after a first metal layer (not shown)of a first metallic material is deposited on a substrate 10, a gateelectrode 15 and a gate line (not shown) are formed by patterning thefirst metal layer through a first mask process including a coating stepfor a photoresist (PR), an exposure step using a mask, a developing stepof the PR and an etching step of the first metal layer. The substrate 10includes a pixel region “P” divided into a transmissive area “TA” and areflective area “RA.” The reflective area “RA” includes a transistorarea “TrA.”

As shown in FIG. 2B, a gate insulating layer 20 is formed on the gateelectrode 15 and the gate line. An intrinsic amorphous silicon layer(not shown), a doped amorphous silicon layer (not shown) and a secondmetal layer (not shown) are sequentially deposited on the gateinsulating layer 20. Then, a data line 30, a semiconductor layer 25,including an active layer 25 a and an ohmic contact layer 25 b, a sourceelectrode 33 and a drain electrode 36, are formed by patterning thesecond metal layer, the doped amorphous silicon layer and the intrinsicamorphous silicon layer through a second mask process.

As shown in FIG. 2C, a first passivation layer 39 is formed on thesource electrode 33, the drain electrode 36 and the data line 30 bydepositing an inorganic insulating material. After coating an organicinsulating material on the first passivation layer 39, a secondpassivation layer 45 is formed by patterning the coated organicinsulating material through a third mask process. The second passivationlayer 45 has an uneven top surface, and includes a drain contact hole 47and a through hole “TH.” The drain contact hole exposes the firstpassivation layer 39 on the drain electrode 36 and the through hole “TH”exposes the first passivation layer 39 in the transmissive area “TA.” Inaddition, a third passivation layer 49 is formed on the secondpassivation layer 39 by depositing an inorganic insulating material.

As shown in FIG. 2D, after a third metal layer (not shown) having arelatively high reflectance is deposited on the third passivation layer49, a reflective plate 52 is formed in the reflective area “RA” of thepixel region “P” by patterning the third metal layer through a fourthmask process. Since the third metal layer corresponding to the draincontact hole 47 and the through hole “TH” is removed, the thirdpassivation layer 49 corresponding to the drain contact hole 47 and thethrough hole “TH” is exposed through the reflective plate 52.

As shown in FIG. 2E, after an inorganic insulating material is depositedon the reflective plate 52, a fourth passivation layer 55 is formed bypatterning the deposited inorganic insulating material through a fifthmask process. Since the fourth passivation layer 55, the thirdpassivation layer 49 and the first passivation layer 39 corresponding tothe drain contact hole 47 are removed, the drain electrode 36 is exposedthrough the drain contact hole 47.

As shown in FIG. 2F, after a transparent conductive material isdeposited on the fourth passivation layer 55. Then, a pixel electrode 60is formed in the pixel region “P” by patterning the depositedtransparent conductive material through a sixth mask process. Thus, thepixel electrode 60 is connected to the drain electrode 36 through thedrain contact hole 47.

As described above, an array substrate for a transflective LCD deviceaccording to the related art is fabricated through a six-mask process.Each mask process includes several steps, such as coating PR, exposureof the PR using a mask, a developing the PR, etching using the developedPR and stripping the developed PR. Accordingly, mask processes areexpensive in terms of both fabrication time and material cost. Inaddition, each mask process introduces an additional probability ofyield reduction.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a transflective LCDdevice and a method of fabricating the same that substantially obviateone or more of the problems due to limitations and disadvantages of therelated art.

An object of the present invention is to provide an array substrate fora transflective LCD device that is fabricated through a five-maskprocess, and a method of fabricating the same.

Another object of the present invention is to provide an array substratefor a transflective LCD device having an improved production efficiency,and a method of fabricating the same.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, an arraysubstrate for a transflective liquid crystal display device includes: asubstrate; a gate line and a data line on the substrate, the gate lineand the data line crossing each other to define a pixel region includinga transmissive area and a reflective area surrounding the transmissivearea; a thin film transistor electrically connected to the gate line andthe data line; a first passivation layer on the thin film transistor,the first passivation layer having a drain contact hole exposing a drainelectrode of the thin film transistor and a through hole exposing thesubstrate in the transmissive area; a pixel electrode on the firstpassivation layer, the pixel electrode contacting the substrate in thetransmissive area through the through hole; a reflective plate on thepixel electrode, the reflective plate being electrically connected tothe drain electrode through the drain contact hole and contacting thepixel electrode.

In another aspect, a method of fabricating an array substrate for atransflective liquid crystal display device includes: forming a gateline and a data line on a substrate, the gate line and the data linecrossing each other to define a pixel region including a transmissivearea and a reflective area surrounding the transmissive area; forming agate insulating layer between the gate line and the data line; forming athin film transistor connected to the gate line and the data line;forming a first passivation layer on the thin film transistor, the firstpassivation layer having a drain contact hole exposing a drain electrodeof the thin film transistor and a through hole exposing the gateinsulating layer on the substrate in the transmissive area; forming asecond passivation layer on the first passivation layer; forming a firstphotoresist pattern on the second passivation layer, the firstphotoresist pattern exposing the drain contact hole and the throughhole; etching the second passivation layer and the gate insulating layerusing the first photoresist pattern as an etch mask such that the drainelectrode is exposed through the drain contact hole and the substrate isexposed through the through hole; forming a transparent conductivematerial layer on the first photoresist pattern; forming a firstphotoresist layer on the transparent conductive material layer;anisotropically removing the first photoresist layer to form a secondphotoresist pattern on the transparent conductive material layer in thedrain contact hole and the through hole; etching the transparentconductive material layer using the second photoresist pattern as anetch mask to form a drain terminal in the drain contact hole and a pixelelectrode in the through hole; removing the first and second photoresistpatterns; and forming a reflective plate on the drain terminal and thepixel electrode, the reflective plate contacting the drain terminal andthe pixel electrode.

In another aspect, an array substrate for a transflective liquid crystaldisplay device includes: a substrate; a gate line and a data line on thesubstrate, the gate line and the data line crossing each other to definea pixel region including a transmissive area and a reflective areasurrounding the transmissive area; a thin film transistor electricallyconnected to the gate line and the data line; a first passivation layeron the thin film transistor, the first passivation layer having a draincontact hole exposing a drain electrode of the thin film transistor anda through hole exposing the substrate in the transmissive area; a pixelelectrode contacting the substrate in the transmissive area and a firstsidewall of the through hole; a drain terminal contacting the drainelectrode and a second sidewall of the drain contact hole; and areflective plate on the first passivation layer, the reflective platecontacting the pixel electrode on the first sidewall of the through holeand covering the drain terminal.

In another aspect, a method of fabricating an array substrate for atransflective liquid crystal display device includes: forming a gateline and a data line on a substrate, the gate line and the data linecrossing each other to define a pixel region including a transmissivearea and a reflective area surrounding the transmissive area; forming agate insulating layer between the gate line and the data line; forming athin film transistor connected to the gate line and the data line;forming a first passivation layer on the thin film transistor, the firstpassivation layer having a drain contact hole exposing a drain electrodeof the thin film transistor and a through hole exposing the gateinsulating layer on the substrate in the transmissive area; forming asecond passivation layer on the first passivation layer; forming a firstphotoresist pattern on the second passivation layer, the firstphotoresist pattern exposing the drain contact hole and the throughhole; etching the second passivation layer and the gate insulating layerusing the first photoresist pattern as an etch mask such that the drainelectrode is exposed through the drain contact hole and the substrate isexposed through the through hole; forming a transparent conductivematerial layer on the first photoresist pattern and on the secondpassivation layer; changing the crystalline state of the transparentconductive material layer such that the crystalline state of firstportions of the transparent conductive material layer on the firstpassivation layer are different than second portions of the transparentconductive material layer over the first passivation layer; forming afirst photoresist layer on the transparent conductive material layer;anisotropically removing the first photoresist layer to form a secondphotoresist pattern on the transparent conductive material layer in thedrain contact hole and the through hole; selectively etching the secondportions of the transparent conductive material layer to form a drainterminal in the drain contact hole and a pixel electrode in the throughhole; removing the first and second photoresist patterns; and forming areflective plate on the drain terminal and the pixel electrode, thereflective plate contacting the drain terminal and the pixel electrode.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a cross-sectional view of an array substrate for atransflective LCD device according to the related art.

FIGS. 2A to 2F are cross-sectional views showing a fabrication processof an array substrate for a transflective LCD device according to therelated art.

FIG. 3 is a plane view of an array substrate for a transflective LCDdevice according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view along line “IV-IV” of FIG. 3.

FIG. 5 is a cross-sectional view along line “V-V” of FIG. 3.

FIG. 6 is a cross-sectional view along line “VI-VI” of FIG. 3.

FIGS. 7A to 7J are cross-sectional views, which along line “IV-IV” ofFIG. 3, showing a fabricating process of an array substrate for atransflective LCD device according to an embodiment of the presentinvention.

FIGS. 8A to 8J are cross-sectional views, which are along line “V-V” ofFIG. 3, showing a fabricating process of an array substrate for atransflective LCD device according to an embodiment of the presentinvention.

FIGS. 9A to 9J are cross-sectional views, which are along line “VI-VI”of FIG. 3, showing a fabricating process of an array substrate for atransflective LCD device according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, similar reference numbers will be used torefer to the same or similar parts.

FIG. 3 is a plan view of an array substrate for a transflective LCDdevice according to an embodiment of the present invention. As shown inFIG. 3, a gate line 113 and a data line 135 are formed on a substrate110. The gate line 113 and the data line 135 cross each other, tothereby define a pixel region “P.” A thin film transistor (TFT) “Tr,” asa switching element, is electrically connected to the gate line 113 andthe data line 135. The TFT “Tr” includes a gate electrode 115, a gateinsulating layer (not shown), a semiconductor layer 125, a sourceelectrode 140 and a drain electrode 143. The semiconductor layer 125 hasan active layer and an ohmic contact layer. A gate pad 117 is formed atone end of the gate line 113, and a data pad 148 is formed at one end ofthe data line 135. Although not shown in FIG. 3, an external drivingcircuit contacts the gate pad 117 and the data pad 148, and supplies agate signal and a data signal through the gate pad 117 and the data pad148, respectively.

The pixel region “P” includes a transmissive area “TA” at a centralportion thereof and a reflective area “RA” surrounding the transmissivearea “TA.” A second passivation layer (not shown) of an organicinsulating material has a through hole (TH) corresponding to thetransmissive area “TA,” and a reflective plate 186 is formed tocorrespond to the reflective area “RA.” The second passivation layer hasan uneven top surface to prevent a mirror reflection at the reflectiveplate 186. The reflective plate 186 is electrically connected to thedrain electrode 143 of the TFT “Tr” through a drain contact hole 158. Apixel electrode 173 of a transparent conductive material is formed inthe transmissive area “TA.” Thus, the pixel electrode is formed at abottom and a sidewall of the through hole “TH,” and contacts thereflective plate 186 at edge portions.

A storage capacitor “StgC” is formed in a boundary of the pixel region“P.” The storage capacitor “StgC” includes a first storage electrode 114of a portion of the gate line 113, a dielectric layer (not shown) of thegate insulating layer on the first storage electrode 114 and a secondstorage electrode 146 on the dielectric layer over the first storageelectrode 114. The second storage electrode 146 is electricallyconnected to the reflective plate 186 through a storage contact hole160.

In this embodiment, the storage capacitor “StgC” has a storage-on-gatestructure where the gate line 113 is used as the first storage electrode114, more particularly, a storage-on-previous gate structure where ann^(th) pixel region uses a (n−1)^(th) gate line as a first storagecapacitor. In another embodiment, however, a storage capacitor can havea storage-on-common structure, where a common line parallel to the gateline is used as a first storage electrode, and a metal patternoverlapping the common line and connected to a pixel electrode through acontact hole is used as a second storage electrode.

FIG. 4 is a cross-sectional view along line “IV-IV” of FIG. 3, and FIG.5 is a cross-sectional view along line “V-V” of FIG. 3. In addition,FIG. 6 is a cross-sectional view along line “VI-VI” of FIG. 3. As shownin FIGS. 4 to 6, a substrate 110 has a pixel region “P” defined by acrossing of a gate line 113 and a data line 135. A gate pad area “GPA”is at one end of the gate line 113 and a data pad area “DPA” is at oneend of the data line 135. A gate pad 117 is formed in the gate pad area“GPA” and a data pad 148 is formed in the data pad area “DPA.” The pixelregion “P” includes a transmissive area “TA” corresponding to a throughhole “TH” and a reflective area “RA” corresponding to a reflective plate186. A transistor area “TrA” where a thin film transistor (TFT) “Tr” isformed and a storage capacitor area “StgA” where a storage capacitor“StgC” is formed can be defined in the reflective area “RA.”

The gate line 113 is formed on the substrate 110 and a gate electrode115 extending from the gate line 113 is formed in the transistor area“TrA” of the reflective area “RA.” A gate insulating layer 120 is formedon the gate electrode 115, and a semiconductor layer 125 is formed onthe gate insulating layer 120. The semiconductor layer 125 can includean active layer 125 a, such as intrinsic amorphous silicon, and an ohmiccontact layer 125 b, such as, impurity-doped amorphous silicon. Theohmic contact layer 125 b is separated into two portions so as to exposethe active layer 125 a between the two portions. Source and drainelectrodes 140 and 143 are formed on the ohmic contact layer 125 b. Thegate electrode 115, the semiconductor layer 125, the source electrode140 and the drain electrode 143 constitute the thin film transistor(TFT) “Tr” as a switching element. The data line 135 crossing the gateline 113 to define the pixel region “P” is formed on the gate insulatinglayer 120. The data line 135 is connected to the source electrode 140 ofthe TFT “Tr.”

The gate pad 117 is formed in the gate pad area “GPA” for connection toone end of the gate line 113 and the data pad 148 is formed in the datapad area “DPA” for connection to one end of the data line 135. In thestorage area “StgA,” a second storage electrode 146 having an islandshape is formed over the gate insulating layer 120 on the gate line 113.The second storage electrode 146 can be formed of the same material asthe source and drain electrodes 140 and 143.

A first passivation layer 150 of an inorganic insulating material isformed on the TFT “Tr,” and a second passivation layer 155 of an organicinsulating material is formed on the first passivation layer 150corresponding to the reflective area “RA.” The second passivation layer155 has an uneven top surface contour that is like the top surface ofthe reflective plate 186, which is subsequently formed over the secondpassivation layer 155. A portion of the second passivation layer 155corresponding to the transmissive area “TA” is removed to form thethrough hole “TH” exposing the substrate 110. In addition, portions ofthe second passivation layer 155 corresponding to the gate pad area“GPA” and the data pad area “DPA” are removed to expose the gate pad 117and the data pad 148. The second passivation layer 155 has a draincontact hole 158 exposing the drain electrode 143 and a storage contacthole 160 exposing the second storage electrode 146 formed by removingportions of the second passivation layer 155.

A third passivation layer 170 of an inorganic insulating material isformed on the second passivation layer 155. Portions of the thirdpassivation layer 170 corresponding to the through hole “TH,” the draincontact hole 158 and the storage contact hole 160 are removed. Inaddition, portions of the third passivation layer 170 corresponding tothe gate pad 117 and the data pad 148 are removed to form a gate padcontact hole 162 and a data pad contact hole 164, respectively. As aresult, the through hole “TH” is formed through the third passivationlayer 170, the second passivation layer 155, the first passivation layer150 and the gate insulating layer 120 in the transmissive area “TA” toexpose the substrate 110. The drain contact hole 158 is formed throughthe third passivation layer 170, the second passivation layer 155 andthe first passivation layer 150 in the transistor area “TrA” to exposethe drain electrode 143. The storage contact hole 160 is formed throughthe third passivation layer 170, the second passivation layer 155 andthe first passivation layer 150 in the storage area “StgA” to expose thesecond storage electrode 146. In addition, the gate pad contact hole isformed through the third passivation layer 170, the first passivationlayer 150 and the gate insulating layer 120 in the gate pad area “GPA”to expose the gate pad 117, and the data pad contact hole 164 is formedthrough the third passivation layer 170 and the first passivation layer150 in the data pad area “DPA” to expose the data pad 148.

A pixel electrode 173 of a transparent conductive material is formed onthe bottom and sidewall of the through hole “TH.” Accordingly, the pixelelectrode 173 contacts the substrate 110 in the transmissive area “TA.”Similarly, a drain terminal 175 of a transparent conductive material isformed in the bottom and sidewall of the drain contact hole 158 tocontact the drain electrode 143, and the storage terminal 177 of atransparent conductive material is formed on bottom and sidewall of thestorage contact hole 160 to contact the second storage electrode 146. Inaddition, a gate pad terminal 180 is formed on the bottom and sidewallof the gate pad contact hole 162 to contact the gate pad 117, and a datapad terminal 182 of a transparent conductive material is formed on thebottom and sidewall of the data pad contact hole 164 to contact the datapad 148.

A reflective plate 186 of a metallic material having a relatively highreflectance is formed on the third passivation layer 170 in thereflective area “RA.” The reflective plate 186 is connected to the pixelelectrode 173, the drain terminal 175 and the storage terminal 177. Thereflective plate 186 contacts the pixel electrode on the sidewall of thethrough hole “TH.” In addition, the reflective plate 186 contacts thedrain terminal 175 on the bottom and the sidewall of the drain contacthole 158, and contacts the storage terminal 177 on the bottom and thesidewall of the storage contact hole 160. The reflective plate 186 isindependently formed in each pixel region “P” and functions as areflective electrode because the reflective plate 186 is electricallyconnected to the drain electrode 143.

FIGS. 7A to 7J, 8A to 8J, and 9A to 9J are cross-sectional views showinga fabricating process of an array substrate for a transflective LCDdevice according to an embodiment of the present invention. FIGS. 7A to7J are along line “IV-IV” of FIG. 3. In addition, FIGS. 8A to 8J arealong line “V-V” of FIG. 3, and FIGS. 9A to 9J are along a line “VI-VI”of FIG. 3.

In FIGS. 7A, 8A and 9A, after a first metal layer (not shown) is formedon a substrate 110, the first metal layer is patterned through a firstmask process to form a gate line 113, a gate electrode 115 extendingfrom the gate line 113 in a transistor area “TrA” of a pixel region “P”and a gate pad 117 at one end of the gate line 113. In the first maskprocess, a first photoresist (PR) layer (not shown) can be formed on thefirst metal layer and can be exposed through a first mask (not shown)having a transmissive region and a blocking region. The exposed first PRlayer is developed to form a first PR pattern, and the first metal layeris etched using the first PR pattern as an etch mask to form the gateline 113, the gate electrode 115 and the gate pad 117.

In FIGS. 7B, 8B and 9B, a gate insulating layer 120 is formed on thegate line 113, the gate electrode 115 and the gate pad 117 by depositingan inorganic insulating material, such as silicon oxide (SiO₂) andsilicon nitride (SiN_(x)). An intrinsic amorphous silicon layer (notshown), an impurity-doped amorphous silicon layer (not shown) and asecond metal layer are sequentially formed on the gate insulating layer120. Through a second mask process, the second metal layer is patternedto form a source electrode 140, a drain electrode 143, a data line 135and a data pad 148, and the impurity-doped amorphous silicon layer andthe intrinsic amorphous silicon layer are patterned to form asemiconductor layer 125 including an active layer 125 a and an ohmiccontact layer 125 b. In the second mask process, a second PR layer (notshown) can be formed on the second metal layer, and can be exposedthrough a second mask (not shown) having a transmissive region, ablocking region and a half-transmissive region such that a transmittanceof the half-transmissive region is greater than a transmittance of theblocking region and smaller than a transmittance of the transmissiveregion. Since the half-transmissive region of the second mask can beobtained from a slit pattern or a half-tone pattern, an exposure stepusing the second mask is referred to as a diffraction exposure or ahalf-tone exposure. The exposed second PR layer is developed to form asecond PR pattern 191 corresponding to the transistor area “TrA,” thestorage area “StgA” and the data pad area “DPA.”

The second PR pattern 191 includes a first portion 191 a having a firstthickness and a second portion 191 b having a second thickness smallerthan the first thickness. The first portion 191 a of the second PRpattern 191 corresponds to a portion where the second metal layer, theimpurity-doped amorphous silicon layer and the intrinsic amorphoussilicon layer remain in a subsequent process, and the second portion 191b of the second PR layer 191 corresponds to another portion where thesecond metal layer is removed and the impurity-doped amorphous siliconlayer and the intrinsic amorphous silicon layer remain in a subsequentprocess. In the transistor area “TrA,” for example, the first portion191 a of the second PR layer 191 corresponds to a portion for source anddrain electrodes and the second portion 191 b of the second PR layercorresponds to another portion for a channel region. Accordingly, thefirst portion 191 a of the second PR layer 191 corresponds to a dataline, a source electrode, a drain electrode, a second storage electrodeand a data pad of a subsequent process, while the second portion 191 bof the second PR layer 191 corresponds to the channel region between thesource and drain electrodes.

The second metal layer, the impurity-doped amorphous silicon layer andthe intrinsic amorphous silicon layer are etched using the second PRpattern 191 having the first and second portions 191 a and 191 b as anetch mask to form a source-drain pattern 138, an impurity-dopedamorphous silicon pattern 123 under the source-drain pattern 138 and anactive layer 125 a under the impurity-doped amorphous silicon pattern123 in the transistor area “TrA.” At the same time, a data line 135crossing the gate line 113, a data pad 148 at one end of the data line135 and a second storage electrode 146 overlapping the gate line 113 areformed by etching the second metal layer, the impurity-doped amorphoussilicon layer and the intrinsic amorphous silicon layer. A portion ofthe gate line 113 overlapping the second storage electrode 146 in thestorage area “StgA” functions as a first storage electrode 114. Here, astorage impurity-doped amorphous silicon pattern 127 a and a storageintrinsic amorphous silicon pattern 127 b having the same shape as thesecond storage electrode 146 are formed under the second storageelectrode 146. Similarly, a data impurity-doped amorphous siliconpattern and a data intrinsic amorphous silicon pattern having the sameshape as the data line 135 are formed under the data line 135.

In FIGS. 7C, 8C and 9C, the second portion 191 b (of FIG. 7B) of thesecond PR pattern 191 are removed by an ashing step to expose a portionof the source-drain pattern 138 (of FIG. 7B). Since the first portion191 a (of FIGS. 7B and 9B) of the second PR pattern 191 has the firstthickness greater than the second thickness, the first portion 191 a ofthe second PR pattern 191 remains even after the second portion 191 b ofthe second PR pattern 191 is removed. The remaining first portion (notshown) of the second PR pattern can have a thickness corresponding to adifference between the first and second thicknesses.

The portion of the source-drain pattern 138 (of FIG. 7B) exposed throughthe remaining first portion of the second PR pattern 191 and theimpurity-doped amorphous silicon pattern 123 (of FIG. 7B) under theexposed portion of the source-drain electrode 138 are etched using theremaining first portion of the second PR pattern 191 as an etch mask toform a source electrode 140, a drain electrode 143 and an ohmic contactlayer 125 b under the source and drain electrodes 140 and 143. Thesource and drain electrodes 140 and 143 are spaced apart from each otherand on opposite sides of the gate electrode 115 in the transistor area“TrA,” and the ohmic contact layer 125 b has the same shape as thesource and drain electrodes 140 and 143. After the source electrode 140,the drain electrode 143 and the ohmic contact layer 125 b are formed,the remaining first portion of the second PR pattern 191 is removed by astripping step.

As shown in FIGS. 7D, 8D and 9D, a first passivation layer 150 of aninorganic insulating material, such as silicon oxide (SiO₂) or siliconnitride (SiN_(x)), is formed on the data line 135, the source electrode140, the drain electrode 143 and the second storage electrode 146. Whenthe active layer 125 a contacts a second passivation layer 155 of anorganic material in a subsequent process, the active layer 125 a can bedegraded by contamination that causes deterioration of the TFT “Tr.” Toprevent such contamination, the first passivation layer 150 prevents acontact between the active layer 125 a and the second passivation layer155. In an alternative embodiment, the first passivation layer 150 canbe omitted when possible degradation of the active layer 125 a isnegligible.

The second passivation layer 155 is formed on the first passivationlayer 150 through a third mask process. An organic insulating materiallayer having a photosensitivity is formed on the first passivation layer150, and is exposed through a third mask (not shown) having atransmissive region, a blocking region and a half-transmissive regionsuch that a transmittance of the half-transmissive region is greaterthan a transmittance of the blocking region and smaller than atransmittance of the transmissive region. For example, when the organicinsulating material layer has a positive type photosensitivity, thethird mask can be aligned such that transmissive regions correspond tothe transmissive area “TA,” the gate pad area “GPA,” the data pad area“DPA,” the drain contact hole 158 and the storage contact hole 160, andalternating blocking and half-transmissive regions correspond to thereflective area “RA.” In the alternative, when the organic insulatingmaterial layer has a negative type photosensitivity, the third mask canbe aligned such that blocking regions correspond to the transmissivearea “TA,” the gate pad area “GPA,” the data pad area “DPA,” the draincontact hole 158 and the storage contact hole 160, and alternatingtransmissive region and the half-transmissive region correspond to thereflective area “RA.”

The organic insulating material layer is exposed through the third maskand the exposed organic insulating material layer is developed to formthe through hole “TH” exposing the first passivation layer 150 in thetransmissive area “TA,” the drain contact hole 158 exposing the firstpassivation layer 150 on the drain electrode 143, and the storagecontact hole 160 exposing the first passivation layer 150 on the secondstorage electrode 146. The second passivation layer can have an uneventop surface due to the half-transmissive region of the third mask. Theround shape of the uneven top surface of the second passivation layer155 can be obtained by an additional heat treatment step.

As shown in FIGS. 7E, 8E and 9E, a third passivation layer 170 of aninorganic insulating material, such as silicon oxide (SiO₂) or siliconnitride (SiN_(x)), is formed on the second passivation layer 155 througha fourth mask process. A third PR layer (not shown) is formed on thethird passivation layer 170 and is exposed through a fourth mask (notshown) having a transmissive region and a blocking region. The exposedthird PR layer is developed to form a third PR pattern 193 exposingportions corresponding to the drain contact hole 158, the storagecontact hole 160, the through hole “TH,” the gate pad area “GPA” and thedata pad area “DPA.” In the alternative, the third passivation layer 170can be omitted.

The third passivation layer 170, the first passivation layer 150 and thegate insulating layer 120 are sequentially etched using the third PRpattern 193 as an etch mask to complete the drain contact hole 158exposing the drain electrode 143, the storage contact hole 160 exposingthe second storage electrode 146, the through hole “TH” exposing thesubstrate 110, the gate pad contact hole 162 exposing the gate pad 117and the data pad contact hole exposing the data pad 148. As a result,the through hole “TH” is formed through the gate insulating layer 120,the first passivation layer 150, the second passivation layer 155 andthe third passivation layer 170, and the gate pad contact hole 162 isformed through the gate insulating layer 120, the first passivationlayer 150 and the third passivation layer 170. In addition, the draincontact hole 158 and the storage contact hole 160 are formed through thefirst, second and third passivation layers 150, 155 and 170. The datapad contact hole 164 is formed through the first passivation layer 150and third passivation layer 170.

As shown in FIGS. 7F, 8F and 9F, a transparent conductive material layer172 is formed on the third PR pattern 193. Accordingly, the transparentconductive material layer 172 is formed on bottoms and sidewalls of thedrain contact hole 158, the storage contact hole 160, the through hole“TH,” the gate pad contact hole 162 and the data pad contact hole 164. Afourth PR layer 195 is formed on the transparent conductive materiallayer 172. Since the fourth PR layer 195 is formed by coating methodhaving an excellent step coverage property, the drain contact hole 158,the storage contact hole 160, the through hole “TH,” the gate padcontact hole 162 and the data pad contact hole 164 are filled up withthe fourth PR layer 195 having a flat top surface.

As shown in FIGS. 7G, 8G and 9G, the fourth PR layer 195 is removed byan ashing method having an anisotropic property. Accordingly, the fourthPR layer 195 is equally removed along a downward direction to expose thetransparent conductive material layer 172 except on the bottoms and thesidewalls of the drain contact hole 158, the storage contact hole 160,the through hole “TH,” the gate pad contact hole 162 and the data padcontact hole 164. Since the transparent conductive material layer 172 isnot removed by the ashing method, the ashing method for the fourth PRlayer 195 can be continuously performed even after the fourth PR layer195 in the reflective area “RA” is removed. As a result, a fourth PRpattern 195 a remains on the bottoms and the sidewalls of the draincontact hole 158, the storage contact hole 160, the through hole “TH,”the gate pad contact hole 162 and the data pad contact hole 164. Thefourth PR pattern 195 a can have a top surface height smaller than a topsurface height of the second passivation layer 155 by controlling timeperiod, or type and amount of gas for the ashing method. Since athickness of the fourth PR layer 195 in the reflective area “RA” is muchsmaller than a thickness of the fourth PR layer 195 in each holes 158,160, “TH,” 162 and 164 due to the third PR pattern 193 and the secondpassivation layer 155, the fourth PR pattern 195 a remains more stably.

As shown in FIG. 7H, 8H and 9H, the transparent conductive materiallayer 172 (of FIGS. 7G, 8G and 9G) is etched using the fourth PR pattern195 a as an etch mask to form a pixel electrode 173, a drain terminal175, a storage terminal 177, a gate pad terminal 180 and a data padterminal 182. More particularly, the transparent conductive materiallayer 172 can be selectively etched leaving the pixel electrode 173based upon the transparent conductive layer 172 on the third PR pattern193 having a different crystalline state than the pixel electrode 173.The difference in crystalline states can be done by a laser process orultraviolet treatment after forming the transparent conductive layer 172or, in the alternative, by a laser or thermal process after forming thefourth PR pattern 195 a.

The pixel electrode 173 contacts the substrate in the through hole “TH.”In addition, the drain terminal 175 and the storage terminal contact thedrain electrode 143 in the drain contact hole 158 and the second storageelectrode 146 in the storage contact hole 160, respectively. Further,the gate pad terminal 180 and the data pad terminal 182 contact the gatepad 117 in the gate pad contact hole 162 and the data pad 148 in thedata pad contact hole 164, respectively.

As shown in FIGS. 7I, 8I and 9I, the third and fourth PR patterns 193and 195 a (of FIGS. 7H, 8H and 9H) are removed by a stripping method toexpose the third passivation layer 170, the pixel electrode 173, thedrain terminal 175, the storage terminal 177, the gate pad terminal 180and the data pad terminal 182.

As shown in FIGS. 7J, 8J and 9J, a reflective plate 186 is formed on thethird passivation layer 170 through a fifth mask process. In the fifthmask process, a third metal layer (not shown) is formed on the thirdpassivation layer 170, the pixel electrode 173, the drain terminal 175,the storage terminal 177, the gate pad terminal 180 and the data padterminal 182, and a fifth PR layer (not shown) is formed on the thirdmetal layer. A metallic material, such as aluminum (Al) or aluminum (Al)alloy, having a high reflectance can be used for the third metal layer.The fifth PR layer is exposed through a fifth mask (not shown) having atransmissive region and a blocking region to form a fifth PR pattern(not shown). The third metal layer is etched using the fifth PR patternas an etch mask to form the reflective plate 186. The reflective plate186 contacts the pixel electrode 173 on the sidewall of the through hole“TH,” and contacts the drain terminal 175 on the bottoms and thesidewalls of the drain contact hole 158 and the storage terminal 177 onthe bottoms and the sidewalls of the storage contact hole 160. As aresult, the reflective plate 186 is electrically connected to the drainelectrode 143, the second storage electrode 146 and the pixel electrode173. Thus, the reflective plate 186 functions as an electrode fordriving a liquid crystal layer of a transflective LCD device in asubsequent process. Since the reflective plate 186 and the pixelelectrode 173 contact each other on the sidewall of the through hole“TH,” it is preferable that the through hole “TH” has a slanted sidewallfor more reliable contact.

In embodiments of the present invention, since an array substrate for atransflective LCD device is fabricated through a five-mask process,production yield is improved and fabrication cost is reduced. Inaddition, since a reflective plate having an uneven top surface isformed at a top of the array substrate, a mirror reflection is preventedand a reflection efficiency is maximized.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-17. (canceled)
 18. A method of fabricating an array substrate for atransflective liquid crystal display device, comprising: forming a gateline and a data line on a substrate, the gate line and the data linecrossing each other to define a pixel region including a transmissivearea and a reflective area surrounding the transmissive area; forming agate insulating layer between the gate line and the data line; forming athin film transistor connected to the gate line and the data line;forming a first passivation layer on the thin film transistor, the firstpassivation layer having a drain contact hole exposing a drain electrodeof the thin film transistor and a through hole exposing the gateinsulating layer on the substrate in the transmissive area; forming asecond passivation layer on the first passivation layer; forming a firstphotoresist pattern on the second passivation layer, the firstphotoresist pattern exposing the drain contact hole and the throughhole; etching the second passivation layer and the gate insulating layerusing the first photoresist pattern as an etch mask such that the drainelectrode is exposed through the drain contact hole and the substrate isexposed through the through hole; forming a transparent conductivematerial layer on the first photoresist pattern; forming a firstphotoresist layer on the transparent conductive material layer;anisotropically removing the first photoresist layer to form a secondphotoresist pattern on the transparent conductive material layer in thedrain contact hole and the through hole; etching the transparentconductive material layer using the second photoresist pattern as anetch mask to form a drain terminal in the drain contact hole and a pixelelectrode in the through hole; removing the first and second photoresistpatterns; forming a reflective plate on the drain terminal and the pixelelectrode, the reflective plate contacting the drain terminal and thepixel electrode; and forming a third passivation layer between the thinfilm transistor and the first passivation layer. 19-25. (canceled)
 26. Amethod of fabricating an array substrate for a transflective liquidcrystal display device, comprising: forming a gate line and a data lineon a substrate, the gate line and the data line crossing each other todefine a pixel region including a transmissive area and a reflectivearea surrounding the transmissive area; forming a gate insulating layerbetween the gate line and the data line; forming a thin film transistorconnected to the gate line and the data line; forming a firstpassivation layer on the thin film transistor, the first passivationlayer having a drain contact hole exposing a drain electrode of the thinfilm transistor and a through hole exposing the gate insulating layer onthe substrate in the transmissive area; forming a second passivationlayer on the first passivation layer; forming a first photoresistpattern on the second passivation layer, the first photoresist patternexposing the drain contact hole and the through hole; etching the secondpassivation layer and the gate insulating layer using the firstphotoresist pattern as an etch mask such that the drain electrode isexposed through the drain contact hole and the substrate is exposedthrough the through hole; forming a transparent conductive materiallayer on the first photoresist pattern; forming a first photoresistlayer on the transparent conductive material layer; anisotropicallyremoving the first photoresist layer to form a second photoresistpattern on the transparent conductive material layer in the draincontact hole and the through hole; etching the transparent conductivematerial layer using the second photoresist pattern as an etch mask toform a drain terminal in the drain contact hole and a pixel electrode inthe through hole; removing the first and second photoresist patterns;and forming a reflective plate on the drain terminal and the pixelelectrode, the reflective plate contacting the drain terminal and thepixel electrode, wherein the forming the thin film transistor includes:forming a gate electrode extending from the gate line; sequentiallyforming an intrinsic amorphous silicon layer, a doped amorphous siliconlayer and a first metal layer on the gate insulating layer; and etchingthe first metal layer, the doped amorphous silicon layer and theintrinsic amorphous silicon layer to form a semiconductor layer on thegate insulating layer over the gate electrode, a source electrode on thesemiconductor layer and the drain electrode spaced apart from the sourceelectrode, and wherein the etching the first metal layer, the dopedamorphous silicon layer and the intrinsic amorphous silicon layercomprises: forming a second photoresist layer on the first metal layer;exposing and developing the second photoresist layer using a mask havingtransmissive region, a blocking region and a half-transmissive regionsuch that a transmittance of the half-transmissive region is greaterthan a transmittance of the blocking region and smaller than atransmittance of the transmissive region to form a second photoresistpattern corresponding to the gate electrode and a third photoresistpattern corresponding to the source electrode, the drain electrode andthe data line, the second photoresist pattern being thinner than thethird photoresist pattern; etching the first metal layer, the dopedamorphous silicon layer and the intrinsic amorphous silicon layer usingthe second and third photoresist patterns as an etch mask to form asource-drain pattern and the data line; removing the second photoresistpattern to expose a portion of the source-drain pattern corresponding tothe gate electrode; etching the first metal layer and the dopedamorphous silicon layer using the third photoresist pattern as an etchmask; and removing the third photoresist pattern.
 27. (canceled)
 28. Amethod of fabricating an array substrate for a transflective liquidcrystal display device, comprising: forming a gate line and a data lineon a substrate, the gate line and the data line crossing each other todefine a pixel region including a transmissive area and a reflectivearea surrounding the transmissive area; forming a gate insulating layerbetween the gate line and the data line; forming a thin film transistorconnected to the gate line and the data line; forming a firstpassivation layer on the thin film transistor, the first passivationlayer having a drain contact hole exposing a drain electrode of the thinfilm transistor and a through hole exposing the gate insulating layer onthe substrate in the transmissive area; forming a second passivationlayer on the first passivation layer; forming a first photoresistpattern on the second passivation layer, the first photoresist patternexposing the drain contact hole and the through hole; etching the secondpassivation layer and the gate insulating layer using the firstphotoresist pattern as an etch mask such that the drain electrode isexposed through the drain contact hole and the substrate is exposedthrough the through hole; forming a transparent conductive materiallayer on the first photoresist pattern and on the second passivationlayer; changing the crystalline state of the transparent conductivematerial layer such that the crystalline state of first portions of thetransparent conductive material layer on the first passivation layer aredifferent than second portions of the transparent conductive materiallayer over the first passivation layer; forming a first photoresistlayer on the transparent conductive material layer; anisotropicallyremoving the first photoresist layer to form a second photoresistpattern on the transparent conductive material layer in the draincontact hole and the through hole; selectively etching the secondportions of the transparent conductive material layer to form a drainterminal the drain contact hole and a pixel electrode in the throughhole; removing the first and second photoresist patterns; and forming areflective plate on the drain terminal and the pixel electrode, thereflective plate contacting the drain terminal and the pixel electrode.29. The method according to claim 28, wherein changing the crystallinestate includes one of a laser process or ultraviolet treatment afterforming the transparent conductive layer.
 30. The method according toclaim 28, wherein changing the crystalline state includes a laser orthermal process after forming the second photoresist pattern.
 31. Anarray substrate for a transflective liquid crystal display device,comprising: a substrate; a gate line and a data line on the substrate,the gate line and the data line crossing each other to define a pixelregion including a transmissive area and a reflective area surroundingthe transmissive area; a thin film transistor electrically connected tothe gate line and the data line; a first passivation layer on the thinfilm transistor, the first passivation layer having a drain contact holeexposing a drain electrode of the thin film transistor and a throughhole exposing the substrate in the transmissive area; a pixel electrodecontacting the substrate in the transmissive area and a first sidewallof the through hole; a drain terminal contacting the drain electrode anda second sidewall of the drain contact hole; and a reflective plate onthe first passivation layer, the reflective plate contacting the pixelelectrode on the first sidewall of the through hole and covering thedrain terminal.
 32. The array substrate according to claim 31, whereinthe reflective plate exposes the pixel electrode on the substrate in thetransmissive area.
 33. The array substrate according to claim 31,wherein the pixel electrode is formed of the same layer as the drainterminal.
 34. The array substrate according to claim 31, furthercomprising a storage capacitor electrically connected to the reflectiveplate, wherein the storage capacitor includes a storage electrode andthe first passivation layer has a storage contact hole exposing thestorage electrode.
 35. The array substrate according to claim 34,further comprising a storage terminal contacting the storage electrodeand a sidewall of the storage contact hole, wherein the reflective platecovers the storage electrode.
 36. The array substrate according to claim35, wherein the storage terminal and the drain terminal are formed ofthe same layer as the pixel electrode.